What must be used when materials are dropped more than 20 feet to any point outside the exterior walls of a building?

When materials are dropped from heights greater than 20 feet to any point outside the exterior walls of a building, safety regulations dictate that an enclosed chute of wood or equivalent material must be utilized. This requirement is in place primarily to prevent accidents that can occur from falling materials, which pose a serious risk to individuals working below.

Using an enclosed chute provides a controlled pathway for materials, significantly reducing the likelihood of injury to workers and passersby. It helps to direct the materials safely to the ground without them scattering or creating hazards in the surrounding area. The enclosed nature of the chute also minimizes the risk of materials catching the wind and being blown away, which can further endanger people and property.

In contrast, other options such as a metal ramp, an open slide, or a temporary scaffold do not adequately address the potential hazards associated with dropping materials from such heights. While ramps and scaffolds serve important purposes in construction, they do not provide the specific protective barrier that an enclosed chute does, thereby failing to meet the safety requirements mandated for scenarios involving high drops.